DESCRIPTION (adapted from the application's abstract): Human T-cell lymphotropic virus type I (HTLV-I) infection causes tropical spastic paraparesis/HTLV-I associated myelopathy (TSP/HAM), is transmitted sexually, parenterally, or perinatally, and is a major public health problem in many parts of the world. The early natural history of sexually acquired HTLV-I infection in young adults remains largely undefined. The candidate's previous studies of female sex workers (FSW) in Peru yielded 2 important findings. First, frequent cervical shedding of HTLV-I DNA among women with sexually acquired HTLV-I infection, as well as a strong association of cervical shedding of HTLV-I DNA with the presence of sexually transmitted diseases, and with young age were found. Second, a blinded, computer assisted quantitative spasticity assessment demonstrated a significantly higher mean spasticity score among asymptomatic FSW with HTLV-I infection, than among uninfected controls. The specific aims of the proposed study are to (1) define clinical and virological features of early HTLV-I infection, (2) to define determinants of cervico-vaginal HTLV-I shedding and the potential role of shedding in sexual transmission, and (3) to define virological and immunological correlates associated with subclinical spasticity and TSP/HAM.